Self-centering cushioning device



Oct. 2, 1956 E. F. RossMAN 2,765,054

SELF-CENTERING CUSHIQNING DEVICE Filed Nov. 12, 1953 l68 ITI Affomey 4 SELF-CENTEG CUSHIONING DEVICE Edwin F. Rossman, Dayton, Ohio, assigner to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application November 12, 1953, Serial No. 391,656

8 Claims. (Cl. 18S-94) This invention relates to a self-centering cushioning device.

It is among the objects of the present invention to provide a self-centering cushioning device which, when secured between a stationary member and a relatively movable member, will cushion the movements of the relatively movable member out of normal position, and, when the force displacing the movable member desists, will return said member to its normal position.

Another object of the present inventionis to provide a self-centering cushioning device for the purpose aforedescribed and capable of providing a greater resistance to movements of the relatively movable member out of normal position in one direction than in the other.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the invention is clearly shown.

In the drawings:

Figure 1 illustrates schematically the installation of the present invention with the gun slighting mechanism in a military tank.

Figure 2 is a longitudinal sectional View of the selfcentering cushioning device, the associated uid flow control mechanism being shown diagrammatically.

Figure 3 is a schematic view illustrating a modified form of iluid flow control mechanism.

The present self-centering cushioning device is illustrated as installed in a military tank for cushioning movements of `the gun out of a selected or aimed posiiton as caused by operation of the tank over rough terrain, the device automatically returning the gun to the selected aimed position after any displacement. The device may as readily be used in any other installation where movements of a member out of normal position due to extraneous forces are resisted in a cushioning manner and when such forces desist, the movable member shall be automatically returned to a selected position.

In Figure l a gun 2l) is shown pivotally mounted upon a carriage 21 in the tank 22. The breech end of the gun is attached to one movable portion of an hydraulic actuator 23, the other movable portion thereof being pivotally attached to an abutment member 24 slidably secured in the gun carriage 21. The actuator 23 is hydraulically operative to raise or lower the breech end of the gun about its pivotal support 19 on carriage 21 for gun aiming purposes. The carrier itself may be rotated back and forth to move the gun in a horizontal plane.

In an installation where the one movable member of the actuator is rigidly anchored to the carriage, vertical thrusts of the comparatively heavy gun barrel due to sudden upward or downward movements of the tank as it is being operated over rough terrain, will react to break the actuator or to move it so that it will act as a pump and develop pressures sulliciently high to burst pressure,

lines leading to the actuator. The present invention eliminates such damaging results by providing a self-centering nite States at@ Patented Oct. 2, 1956 cushioning device between the one movable member of the actuator and the stationary gun carriage, said device cushioning the shocks due to sudden upward or downward thrusts of the gun and finally moving the gun back to the previously aimed position when such gun thrusts no longer occur.

The self-centering cushioning device is illustrated in Figure 2 where the cylinder 30 is shown rigidly anchored to the carriage 21 by bolts 21a. Cylinder 3i) has interior bore portions of two different diameters thereby forming an inner annular shoulder 31.

The outer end of the larger diameter bore is interiorly threaded to receive the cap 32, the interior rim of which forms a shoulder 33 predeterminately spaced from the shoulder 31. A locking screw ring 34 locks the cap in adjusted position in cylinder 30.

Two pistons 40 and 41 reciprocate in cylinder 30, piston 40 in the smaller diameter portion of the cylinder and piston 41 in the larger diameter portion. Piston 40 has a sealing ring 42 provided in an outer annular groove in piston 49, said ring substantially preventing iluid leaks from `this end of the cylinder. An outwardly extending annular ange 43 at the inner end of piston 40 engages shoulder 31 to limit the movement of piston 4t) outwardly of the cylinder. Piston 41 is also provided with a sealing ring 45 which slidably engages the wall or" the cylinder to prevent fluid leakage. Normally piston 41 engages the inner edge 33 of the cap 32 which limits the movement of piston 41 outwardly of the cylinder. Thus, shoulders 31 and 33 in the cylinder determine the maximum spacing of pistons 40 and 41 within the cylinder.

Both pistons 40 and 41 are centrally bored slidably to receive a rod 50, the rod supporting bore in each piston having a sealing ring substantially preventing fluid leaks between the rod and the respective pistons. Rod 50 has an enlarged head 51 engageable with the outer end of piston 41 and providing an abutment therefore normally engaging the piston when said piston is seated upon the rim 33 of cap 32. A similar abutment 53 is threadedly attached to the end of rod Sti protruding from the piston 40 so that said abutment may be adjustable to have it engage the piston 40 normally when said piston engages the shoulder 31 within the cylinder. A pin 54 passing through the abutment 53 and rod 50 locks the two together in properly adjusted relation. Abutment 53 provides a clevis 55 which is attachable to the arm 24 `slidably secured to the rigid carriage 21. Thus the piston rod 50 of the cushioning device is operatively connected to the one movable member of the actuator 23, the slidable arm 24 merely maintaining them in alignment while permitting them to move in a vertical line in response to gun thrusts as the tank is operated over a rough terrain.

Fluid under pressure urges the pistons 40 and 41 in their normal positions in which they engage the respective shoulders 31 and 33 as shown in Figure 2. This Huid under pressure is directed from a source of supply, not shown, through a conduit 66 into the cylinder space 61 between the pistons 46 and 41. Conduit has a spring loaded check valve 62 which permits fluid i'low in one direction only, that is, toward the cylinder 30. Figure 2 shows conduit 6l) as having a branch pipe 63 leading therefrom between the check valve 62 and the inlet port to the cylinder. This pipe 63 communicates with a valve chamber 64 in which a check valve 65 is urged by spring 66 to close pipe 63 thus normally cutting ofi communication of pipe 63 with chamber 64 from which a pipe 67 leads to any suitable fluid sump or supply, not shown. This sump or supply may be the one from which the iluid pressure supply device obtains its fluid to be delivered to the cylinder under predetermined pressure.

Fluid pressure from the source, passing through conduit 60 to cylinder chamber 61 is constantly being exerted against valve 65 to open it, however, spring 66 is so calibrated that a predetermined increase in pressure is necessary to effect actuation of valve 65 so that communication between pipe 63 and chamber 64 is established. Thus the duid pressure from the source of supply is normally not suiciently high to open valve 65. Such `an increase of iluid pressure in chamber 61 and consequently in pipe 63 communicating therewith is developed by the approaching movement of one piston relative to the other.

As has previously been stated, actuator 23 is hydraulically operated to raise and lower the breech end of the gun Ztl about its pivotal support 19 on the carriage 21 for aiming purposes. As long as the tank is being operated over level or comparatively smooth ground gun 2t) will not be appreciably urged vertically about its pivotal support 19. However, if the terrain becomes rough, then the front end of the tank will suddenly be thrust up or down the inertia of the comparatively heavy gun barrel causing vertical pivotal movement thereof relatively to the carriage 21. This is where the present invention becomes effective to cushion such sudden movements of the gun and thereby avoid damage. Supposing the front end of the tank is suddenly thrust upwardly by striking a substantial bump or large rock in the terrain, as a result thereof the barrel of the gun 20 is thrust downwardly relatively to the tank and the breech end of the gun upwardly. As the breech moves upwardly the piston 41 will be moved toward piston itl by the rod 50 and by virtue of its connection through the actuator 23 with said breech. As piston 41 moves to approach piston 40 it will exert a compressing eiort upon the iluid under a predetermined pressure in chamber 61. This increased iluid pressure in chamber 61 is directed against valves 62 and 65, closing valve 62 due to the higher pressure and operating valve 65 to open communication between the pipe 63 and chamber 64 leading to the sump. The upward movement of piston 41 is resisted by the restriction to duid discharge offered by valve 65.

An upward thrust of the gun barrel and consequent downward thrust of the breech thereof results in a downward movement of piston toward piston 41. Now piston 43 exerts a pressure upon the iluid in chamber 61, raising the uid pressure above the predetermined constant pressure and thus again causing a restricted pressure relief flow to be established to the sump past the valve 65. Thus this movement of the gun is again resisted and cushioned.

As soon as the tank thrust tending to move the gun relatively to the tank is over, movement of either piston ttl or l stops, thus piston pressure upon the fluid in chamber 61 ceases to permit the fluid pressure therein to drop to normal. At this time spring 66 will again operate valve 65 to close pipe 63. New, the normal fluid pressure from the source of supply will move the previously mechanically actuated piston 46 or 41 into its normal shoulder engaging position, spaced from the com pani-on piston, thereby re-establishing the gun to its previous, aimed position from which it was suddenly moved by the thrust of the tank upwardly or downwardly. Thus, the device of the present invention not only cushions sudden upward or downward thrusts of the breech end of the gun, but it also returns said gun to its previous position after being moved out of such position vertically by the thrust of the tank as it engages irregularities in the terrain over which it is being operated.

Figure 3 illustrates a modiiied form of pressure control. Here the conduit 61D with check valve 62, leads to the cylinder intake port 150 of the chamber 61 as in Fig. 2. An opening 163 in conduit 66, comparable to pipe 63 of Fig. 2, communicates with chamber 164 which has a recess forming a cylinder 168 in which a piston 169 is slidably supported. This piston 169 has a stem to which valve 165 is secured, said valve being urged to close opening 163 by spring 171 within chamber 164. A duct 172 provides communication between the cylinder 168 behind piston 169 therein and the conduit 60 between valve 62 and the source of fluid pressure in the conduit 60. Another duct 167 leads from chamber 164 to any suitable fluid sump or source of supply. The areas of the piston 169 and the valve 16S exposed to the predetermined fluid pressure provided by the source of fluid pressure being equal, valve 16S will be balanced and therefore will substantially remain inoperative as far as normal uid pressure is concerned. Spring 171 is predeterminately calibrated in order that valve 165 is urged to close port or opening 163 and keep it closed until a predetermined iluid pressure in excess of the normal predetermined pressure from the source of supply is exceeded by movements of piston 40 or 41. When excessive fluid pressure is developed by movements of piston 4@ or 41 one toward the other, such pressure is directed against valve 165 and it will be moved against the opposing effort of spring 171 to open port 163 and thereby establish a restricted fluid pressure relieving iiow into the chamber 164 and through duct 167 to the fluid sump. Portions of conduit 60, 67, or 167 should be of a liexible nature so as to permit oscillations of the gun carriage to allow for aiming of the gun horizontally.

Figure 2 shows the piston 41 of greater transverse dimensio-n than piston 40 to obtain a load differential at the same pressure per square inch within the chamber 61. This favors upward thrusts of the gun breech and offers greater resistance thereto than to the downward thrusts of the breech inasmuch las upward thrusts of the front end of the tank as it meets an obstruction are generally more severe and sudden than downward thrust resulting from the tank dropping into a rut or ditch. The resilient bellows-like structure is provided between the stationary cylinder 30 and the movable abutment 53 and surrounds telescopically engaging piston 40 and its cylinder portion to avoid accumulation of dust or dirt.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted as may come within the scope of the claims which follow.

What is claimed is as follows:

1. A self-centering cushioning mechanism comprising in combination, a stationary cylinder; two pistons in the cylinder spaced apart to form a iluid chamber therebetween; spaced stop means in the cylinder engaged by the pistons for preventing separating movements of the piston beyond a predetermined limit; a rod slidably extending through each piston, said rod having abutments immovably attached thereto, each engaging the outer end of a respective piston when said pistons engage the respective stop means, one of said abutments forming an attachment element; a source of fluid pressure connected to said uid chamber for yieldably urging both pistons against their respective stop means; and means operative at a greater iiuid pressure than that provided by the pressure source and connected with said chamber for venting excess iluid pressure built up in said chamber by movement of either piston toward the other in response to actuation of the rod in one direction or the other longitudinally.

2. A control mechanism for yieldably resisting movement of an attached member out of normal position and for returning said member to its normal position when moved therefrom, said device consisting of a fixed cylinder having two, spaced internal shoulders forming stops; two pistons reciprocative in the cylinder each piston normally engaging one of said cylinder shoulders and thereby forming a chamber therebetween; a rod slidably extending through both pistons said rod having an abutment member attached to its one end, said abutment member normally engaging the outer end of the one piston when said piston engages the adjacent cylinder shoulder; an

attachment ring secured to the other end of the rod, forming an abutment engaged by the second piston when said piston engages the cylinder shoulder adjacent thereto; means for introducing fluid at a predetermined pressure into the chamber between the pistons yieldably to urge the pistons against their respective cylinder shoulders and rod abutments; and iiuid pressure relief means communicating with said chamber, said relief means being connected to a tluid sump and being operative to establish a pressure relief ow only in response to tluid pressure exceeding the predetermined pressure of the iluid introduced into said chamber, said excessive pressure being established by the movement of either piston toward the other in response to longitudinal movement of the rod.

3. A self-centering cushioning device comprising in combination; a cylinder in which two oppositely disposed pistons are yieldably urged apart and into engagement with spaced positive stops in the cylinder by fluid pressure in the cylinder between said pistons; a rod slidably extending through both pistons, said rod having an abutment at its one end engaging the one piston; an attachment member adjustably secured to the other end of the rod and providing an abutment engaging the outer end of the other piston, the respective abutments on the rod engaging the pistons when said pistons engage the stops in the cylinder; a source of predetermined fluid pressure communicating with the cylinder between said pistons for urging the pistons against their respective cylinder stops; and a vent in communication with the cylinder space between said pistons, said vent being operative to exhaust tluid pressure exceeding the predetermined tiuid pressure from the source, said excess pressure being established by reciprocation of one piston toward the other piston.

4. A self-centering cushioning device comprising in combination; a cylinder in which two oppositely disposed pistons are yieldably urged apart and into engagement with spaced positive stops in the cylinder by uid pressure in the cylinder between said pistons; a rod slidably extending through both pistons, said rod having an abutment at its one end engaging the one piston; an attachment member adjustably secured to the other end of the rod and providing an abutment engaging the outer end of the other piston, the respective abutments on the rod engaging the pistons when said pistons engage the stops in the cylinder; a conduit leading from a source of predetermined iluid pressure into the cylinder space between the pistons; a pipe connected to the conduit and leading into a fluid sump said pipe having a fluid flow control device normally closing the pipe and operative only at a fluid pressure exceeding the iluid pressure coming from the source to open the pipe and relieve the excess pressure, said exceeding fluid pressure being established by rod actuation of one piston toward the other.

5. A self-centering cushioning device comprising in combination; a cylinder in which two oppositely disposed pistons are yieldably urged apart and into engagement with spaced positive stops in the cylinder by fluid pressure in the cylinder between said pistons; a rod slidably extending through both pistons, said rod having an abutment at its one end engaging the one piston; an attachment member adjustably secured to the other end of the rod and providing an abutment engaging the outer end of the other piston, the respective abutments on the rod engaging the pistons when said pistons engage the stops in the cylinder; a conduit connected to a source of predetermined iluid pressure and to the cylinder space between the pistons; a vent pipe; a fluid pressure balanced valve in communication with said conduit, said balanced valve being operative only at a pressure exceeding the predetermined fluid pressure from the source for connecting the conduit with the vent pipe; and resilient means urging the balanced valve into conduit closing position, said means loading said valve to hold it closed until a selected fluid pressure exceeding said predetermined pressure from the source is attained by rod movement of one piston toward the other.

6. A device in accordance with claim 3, in which the cylinder has two diferent interior diameter portions each portion slidably supporting a piston, whereby a greater opposing force to the movement of the rod in one direction is obtained than the force opposing the movement of the rod in the opposite direction.

7. A self-centering cushioning device comprising in combination, a cylinder having a bore of two, predetermined ditferent diameters; a piston slidably positioned in each cylinder bore portion, said pistons being spaced to provide a chamber therebetween; positive stops in the cylinder engaged by the pistons to limit their separating movements in the cylinder; a rod slidably extending through both pistons one end of the rod having an abutment secured thereto engaging the one piston; an attachment member adjustably secured to the other end of the rod and forming an abutment engaging the other piston; a conduit connected to a source of predetermined iluid pressure and communicating with the cylinder chamber between the pistons; said pressure normally yieldably urging each piston against its adjacent step and the adjacent abutment on the rod; and a pipe connected to the conduit and to a uid sump, said pipe having a Valve holding the pipe closed against the said predetermined tluid pressure but being operative at a pressure predeterminately exceeding said pressure from the source, said excess pressure being established by the approaching movement of one piston toward the other in response to longitudinal movement of the rod in one direction or the other.

8. A device in accordance with claim 7 in which the cylinder has interior bores of two different diameters and the piston reciprocative in the smaller cylinder portion is the one engaged by the attachment member secured to the rod.

References Cited in the tile of this patent UNITED STATES PATENTS 632,744 Petsche Sept. 12, 1899 FOREIGN PATENTS 354,920 Germany June 16, 1922 

